3rd generation partnership project (3GPP) protocol system includes long term evolution (LTE) standards and universal mobile telecommunications system (UMTS) standards. Since an initial version of UMTS is prior to an initial version of LTE, compared with LTE network, the UMTS network has a broad coverage and user equipment (UE) supporting the UMTS network has a great penetration in early stage of LTE network deployment. Therefore, in a common network cabling manner, the UMTS network covers a wide range and the LTE network is adapted to cover hotspots.
In conventional technology, when an operator provides coverage of both the UMTS network and the LTE network for UE, carriers in UMTS and carriers in LTE are aggregated, i.e., data transmission between a network node and the UE may be performed in a UMTS mode or a LTE mode. To improve a transmission speed of downlink data, the UE may support downlink transmission in two modes. To save transmission costs of the UE and the network node, the UE may only need to implement uplink transmission technology in one mode, while the network node only needs to implement uplink receiving technology in one mode.
However, a method of feeding back ACK/NACK is still used when each downlink transmission mode has a corresponding uplink transmission channel. That is, after receiving downlink data of the LTE network, the UE feeds back ACK/NACK corresponding to the downlink data in an uplink resource of the LTE network; or after receiving downlink data of the UMTS network, the UE feeds back the ACK/NACK corresponding to the downlink data in an uplink resource of the UMTS network.
Therefore, when the UE can receive both the downlink data of the LTE network and the downlink data of the UMTS network, but only supports UMTS uplink or LTE uplink, a problem for transmitting ACK/NACK in one network mode through an uplink resource of another network mode is needed to be solved.